This case series describes the anaesthetic management of two sibling Bengal tiger (Panthera tigris tigris) cubs that were found to have spontaneous femur fractures due to severe nutritional secondary hyperparathyroidism. Both cubs received a combination of medetomidine (25 µg/kg) and ketamine (4 mg/kg) intramuscularly and were maintained with isoflurane in oxygen. An epidural injection of morphine (0.1 mg/kg) and ropivacaine (1.6 mg/kg) was administered to both tigers, which allowed a low end-tidal isoflurane concentration to be maintained throughout the femur fracture reduction operations. Both cubs experienced profound bradycardia and hypotension during general anaesthesia, and were unresponsive to anticholinergic treatment. Possible causes for these cardiovascular complications included: drug pharmacodynamics (medetomidine, morphine, isoflurane), decreased sympathetic tone due to the epidural (ropivacaine) and hypothermia. These possible causes are discussed in detail.